NEW YORK (CNN) -- A former CIA agent who participated in interrogations of terror suspects said Tuesday that the controversial interrogation technique of "waterboarding" has saved lives, but he considers the method torture and now opposes its use.

Ex-CIA agent John Kiriakou says he underwent waterboarding in training and cracked in a few seconds.

Former CIA operative John Kiriakou also told CNN's "American Morning" that he disagrees with a decision to destroy videotapes of certain interrogations, namely of al Qaeda's Abu Zubayda. Kiriakou made the remarks as two congressional committees prepared to grill CIA Director Michael Hayden on the destruction of the tapes and on "alternative" means of interrogation.

Waterboarding begins by placing a suspect on a table with the suspect's feet slightly elevated, said Kiriakou, who was waterboarded several years ago as part of his CIA training. He said he elected not to learn how to perform the technique, which is designed to emulate the sensation of drowning.

"There is a bladder, or a water source, above the head with water pouring down on the mouth, so no water is going into your mouth, but it induces a gag reflex and makes you feel like you're choking," Kiriakou said. Watch the ex-agent describe the procedure »

Kiriakou said he lasted only a few seconds during his training because his body felt like it was seizing up almost immediately.

"It's entirely unpleasant," Kiriakou said. "You are so full of tension that you tense up, your muscles tighten up. It's very uncomfortable."

Abu Zubayda lasted a little longer, said Kiriakou, but not much.

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The former agent, who said he participated in the Abu Zubayda interrogation but not his waterboarding, said the CIA decided to waterboard the al Qaeda operative only after he was "wholly uncooperative" for weeks and refused to answer questions.

All that changed -- and Zubayda reportedly had a divine revelation -- after 30 to 35 seconds of waterboarding, Kiriakou said he learned from the CIA agents who performed the technique.

The terror suspect, who is being held at Guantanamo Bay, Cuba, reportedly gave up information that indirectly led to the the 2003 raid in Pakistan yielding the arrest of Khalid Sheikh Mohammed, an alleged planner of the September 11, 2001, attacks, Kiriakou said.

The CIA was unaware of Mohammed's stature before the Abu Zubayda interrogation, the former agent said.

"Abu Zubayda's the one who told us that Khalid Sheikh Mohammed was so important in the al Qaeda structure, and we didn't realize at the time how important he was," Kiriakou said.

Abu Zubayda also divulged information on "al Qaeda's leadership structure and mentioned people who we really didn't have any familiarization with [and] told us who we should be thinking about, who we should be looking at, and who was important in the organization so we were able to focus our investigation this way," Kiriakou said.

Abu Zubayda reportedly told the agent who waterboarded him that "Allah had visited him in his cell during the night and told him to cooperate because it would make it easier on the other brothers who had been captured," Kiriakou said.

Though the information wrenched from Abu Zubayda "stopped terrorist attacks and saved lives," Kiriakou said he opposes waterboarding.

"Now after all these years, time has passed, and we're more on our feet in this fight against al Qaeda, and I think it's unnecessary," he said.

In a separate CNN interview, Kiriakou said the Justice Department and National Security Council reportedly approved waterboarding and other "alternative" interrogation techniques in June 2002.

"It was a policy decision that came down from the White House," he said.

Despite the executive blessing, Kiriakou and other agents were conflicted over whether to learn the technique, he said.

"One senior officer said to me that this is something you really have to think deeply about," the former agent said, adding he "struggled with it morally."

Kiriakou conceded his position might be hypocritical and said that the technique was useful -- even if he wanted to distance himself from it.

"Waterboarding was an important technique, and some of these other techniques were important in collecting the information," he said. "But I personally didn't want to do it. I didn't think it was right in the long run, and I didn't want to be associated with it."

As for the tapes of the interrogations, Kiriakou -- who claims neither he nor the other CIA agents realized they were being recorded during the Abu Zubayda interrogation -- said he disagrees with the decision to destroy the tapes.

"I don't see the reason to destroy them," Kiriakou said. "There's a possibility that they could be used in a criminal investigation, and frankly, for the historical record, I think it's important to have things like that maintained."

The Justice Department and CIA have announced a preliminary inquiry into the matter. Hayden, the CIA director, is slated to go before congressional committees Tuesday and Wednesday.

Hayden has said the CIA destroyed the tapes "only after it was determined they were no longer of intelligence value and not relevant to any internal, legislative or judicial inquiries."

Congressional leaders said they were never properly notified about the decision.E-mail to a friend